Hmmm, yes ... I now see what you mean.
Closing price $68.84 at 16h00 EST.
In total, under 2500 shares of DUG were traded between 16h00 - 20h00 EST, most at prices nearish to the closing price ($68.84).
But 660 shares (i.e. about 25% of the volume traded in the after market session) were...